Is electrical muscle stimulation a marketing scam or does it really build muscle?

Build muscle: Dr.Kots was able to show, using a tensiometric device, that the muscle tension produced in a maximal ems contraction can be up to 30% higher than a maximal voluntary contraction. This finding was corroborated by independent studies and makes intuitive sense, given the nature of the body's energy conservation system. This paper was published 1973 in montreal concordia univ by dr.Kots of ussr.